In the semiconductor manufacturing process, a layer of the photoresist liquid is coated on a wafer by a spin-coater before a photolithographic process. Because the demand for the semiconductor device is severe, the yield of the wafer may be reduced if there is an impurity remained on the wafer. That is, if any particle or bubble is retained in the photoresist liquid, then the quality of the wafer may be reduced. Therefore, the impurities of the photoresist liquid must be removed before that the liquid is applied on the surface of the wafer.
Please refer to FIG. 1 which is a diagram showing the apparatus for supplying the photoresist liquid of the prior art. The conventional apparatus includes a container 12 filled with the photoresist liquid 11 and a filter 15. The container 12 is placed straight in a hermetic receiver 13. A pipe 14 is inserted into the container 12 and connected to the filter 15. A nitrogen gas (N.sub.2) is introduced into the receiver 13 through a valve 16. After the gas enters the receiver 13, the photoresist liquid 11 is discharged from the container 12 because of the pressurization 17 of the nitrogen gas. The photoresist liquid 11 enters the filter 15 through the pipe 14. The impurities of the photoresist liquid, including particles and bubbles, are removed by the filter 15. Finally, the photoresist liquid 11 is introduced into the spin-coater and then coated on the wafer.
However, there are two shortcomings of the apparatus for supplying the photoresist liquid in the prior art. First, there is a recess at the bottom 18 of the container 12 so the bottom surface of the container is uneven. If the pipe 14 is short and can not be inserted into the recess, there will be a distance between the pipe 14 and the bottom 18 of the container 12. Therefore, the photoresist liquid in the recess can not be discharged from the container 12, and a lot of photoresist liquid 11 will be retained in the container 12. On the contrary, if the pipe 14 is long enough to reach the bottom 18 of the container 12, the photoresist liquid 11 may not be discharged easily. That will waste a lot of photoresist liquid.
Second, all kinds of impurities must be removed by the filter 15. The only one filter may be exchanged frequently and the cost of the semiconductor chip will be increased. Therefore, it is tried by the applicant to deal with the problems encountered with the prior art.